How do I know the volume of my nodule?

The report usually gives three measurements in centimeters, and the volume is calculated from them and is sometimes written in milliliters. If it is not, we calculate it at the consultation from your ultrasound.

How long is the interval between sessions?

The follow-up ultrasound decides it, not a fixed interval: we need to see how much was reabsorbed and how much tissue is still viable. At the evaluation, we tell you when that follow-up ultrasound would take place.

Can a 40 mL nodule be treated?

The guidelines set no upper limit, but they warn that very large nodules respond less well. Each case is assessed with the ultrasound in front of us. In some cases the honest answer is that surgery is the better solution, and we tell you so.

Does the second session carry the same risk as the first?

It is the same procedure on less tissue, with the same precautions. Complications are uncommon in both, and the nerve that controls the voice is protected in the same way.

Large nodules: why sometimes two ablation sessions

Large nodules: why two ablation sessions are sometimes needed.

Above a certain size, the heat of a single session does not reach the whole nodule, and the reason lies in how the heat works rather than in any failure of the technique. It helps to know the volume at which the guidelines start to warn, what a second session achieves according to the trial that tested it, and why it is best to know this before the cost is discussed.

Dr. Joan JacoboSurgical oncologist, thyroid specialist

In short

Nodules over 20 mL respond less to a single session: in the literature, 64.5% success versus 81 to 87% in smaller ones.
A second session is planned when the follow-up ultrasound shows viable tissue that still adds volume, and in the randomized trial that tested this approach, large nodules benefited most.
In a very large nodule, surgery may be the more direct path, and we tell you so at the evaluation. If a second session is needed, it is included in the cost estimate.

The of a nodule is rarely discussed, yet it is the figure that most changes what you can expect from ablation. A nodule measuring 4 by 3 by 3 centimeters is about 19 milliliters, and one measuring 5 by 4 by 3 is about 31. Above 20 milliliters, the guidelines warn that one session may not be enough.

What 20 mL means and why the line is drawn there

Radiofrequency heat treats the nodule zone by zone, moving the electrode tip from one spot to the next, because each position heats a small volume. In a medium-sized nodule, the whole nodule is covered in one session. In a large one, either tissue is left untreated at the edges, or the session runs longer than is advisable. And there is a second reason: near the nerve that controls the voice, the trachea and the blood vessels, a safety margin is left on purpose, and in a large nodule that margin contains more tissue.

64.5%success in nodules over 20 mL with one session, versus 81 to 87% in smaller ones, according to the Korean guideline. Volume predicts the response, but it is not an exclusion criterion.KSThR 2017. Korean J Radiol. 2018, 19(4): 632-655.
30patients with symptomatic solid nodules were randomly assigned to one or two sessions in the trial that tested it: one session was enough for most, and the second benefited large nodules above all, particularly those over 20 mL.Huh JY, Baek JH et al. Radiology. 2012, 263(3): 909-916.

What is left after the first session

The treated nodule is reabsorbed over months. At each follow-up ultrasound, the question is not only how much the nodule shrank but whether an untreated, still viable portion remains, almost always at the edge. It can be recognized on ultrasound by its appearance and, with , by its blood flow. Over time, that portion is what causes one in ten nodules to . In a large nodule, it is more likely to be there from the start.

How the second session is decided

01The first sessionEverything that can be treated safely is treated. In a large nodule, the realistic goal of this session is to bring the volume down and relieve the pressure, not to eliminate it entirely.
02The follow-up ultrasoundThe volume is measured and the edges are checked for viable tissue. If the nodule shrank as expected and the symptoms have resolved, nothing more is needed. If a viable portion with significant volume remains, a second session is planned.
03The second sessionIt is the same outpatient procedure under local anesthesia, aimed only at the tissue that remains. It is usually shorter, and its cost is given to you in writing in advance.
04Or surgeryWhen the nodule is very large, when there are many nodules or when the goiter extends into the chest, surgery offers a more complete solution in a single procedure. We explain this at the evaluation, with your ultrasound in front of us.

Why the second session is mentioned from the start

If your nodule is over 20 mL, the possibility of a second session is not a surprise that comes up at a follow-up visit: it is known from the first ultrasound. That is why it is explained at the evaluation and put in writing, with its cost. And that is why, for a large nodule, a cost estimate that does not mention a second session is incomplete.

Sources

Kim JH et al. 2017 Thyroid Radiofrequency Ablation Guideline: Korean Society of Thyroid Radiology. Korean J Radiol. 2018, 19(4): 632-655.
Huh JY, Baek JH, Choi H, Kim JK, Lee JH. Symptomatic benign thyroid nodules: efficacy of additional radiofrequency ablation treatment session, prospective randomized study. Radiology. 2012, 263(3): 909-916.
Bernardi S et al. Front Endocrinol. 2020, 11: 582550.
Russell JO et al. Surgery. 2024, 175(1): 139-145.